1. Field of The Invention
The present invention relates generally to a hydraulic shock absorber for a vehicle. More particularly, the invention relates to a hydraulic shock absorber which has a low friction seal for allowing a piston rod to be displaced smoothly.
2. Description of The Background Art
A Japanese Utility Model First Publication No. 58-97334 discloses a conventional inverted type shock absorber. This shock absorber includes generally upper and lower chambers which are defined by a piston in a cylinder and a reservoir chamber in an upper end section of the upper chamber which is defined by a base member. For sealing a rod guide member, a single seal member is provided which seals a clearance between a piston rod and a rod hole.
However, the single seal member of the prior art shock absorber requires high pressure in contacting the piston rod and the rod hole for establishing a liquid-tight seal, causing friction thereon to be increased. This results in low durability of the seal member and unsmooth displacement of the piston rod. Therefore, if the prior art shock absorber is applied to an automatic vehicle, it is uncomfortable to drive.